The present invention relates generally to a solid-state laser and, more particularly, to a solid-state laser which compensates for temperature fluctuations and which is easily and inexpensively manufactured.
Solid-state lasers which generate a visible laser beam are used extensively in the construction and agricultural industries for surveying, measurement and equipment control. Consequently, manufacturers are continually attempting to develop more reliable and less expensive lasers.
Laser malfunctions are commonly caused by temperature fluctuations of the laser cavity. The heat generated during conventional laser operation may cause thermally induced elongation of the laser cavity. Previous laser designs have addressed this problem through the use of materials having a low coefficient of thermal expansion, such as Invar, quartz and various ceramics, and also by providing external temperature control to thermally stabilize the laser cavity.
U.S. Pat. No. 4,731,795 issued to Clark et al. discloses an optically pumped solid-state laser wherein the various laser components are positioned in a two-piece, tubular support structure. The tubular support structure has indentations which receive the various laser components and arrange the components along an optical path. The tubular support structure is composed of a rigid material, such as metals, ceramics, glass, thermoplastic materials and thermosetting materials. A preferred material from which to fabricate the support structure is die cast aluminum.
Another solid-state laser design is disclosed in U.S. Pat. No. 4,730,335 also issued to Clark et al. This solid-state laser includes a plurality of fittings having one or more laser components mounted therein. The fittings are constructed in such a manner that the components are aligned with respect to one another along an optical axis upon joining the fittings together.
Each of the Clark et al. lasers is fabricated from a single material. If the laser cavity is manufactured from a material having a low coefficient of expansion, temperature fluctuations have a negligible effect on the length of the laser cavity. Although a laser cavity fabricated from a material having a high coefficient of expansion would expand and contract with temperature fluctuations, the Clark et al. lasers are comprised of a single material and, therefore, every component mounted within the laser is displaced a substantially proportional amount. However, problems exist in situations which ideally require nonuniform displacement of the components to maintain a uniform laser beam. For instance, it may be desired that the pump diode maintain a constant relationship with the laser cavity as the laser cavity expands and contracts.
In addition, prior lasers have used laser mirrors having a ground and polished glass substrate. The glass substrates need to be finely ground and highly polished to reduce losses in the laser. Unfortunately, laser mirrors having such glass substrates are relatively expensive and, therefore, comprise a substantial portion of the cost of prior lasers.
Accordingly, there is a need in the art for a solid-state laser which compensates for temperature fluctuations of the laser and which is easily and inexpensively manufactured.